The present invention relates generally to the field of preparing a substrate for use in immunoassays. Specifically, the invention provides a method of directly coating biological materials on a glass surface.
A “sandwich” immunoassay measures an analyte that is bound between two antibodies; namely the capture antibody and the detection antibody. Sandwich immunoassays are utilized as a tool to specifically identify and/or detect analytes such as bacteria, fungi, viruses, and protozoa in samples. Capture molecules, such as antibodies, bind to the target cells and capture them while other debris and non-target cells in the sample are washed away.
In assays that require capture molecule attachment to an impervious substrate such as a glass slide, the glass surface must be coated with silane. A cross-linker molecule is used to cross-link the silane to the capture molecule. The chemistry involved in the silanization and cross-linking process is tedious and must be performed in the absence of oxygen using toluene, which is flammable, as the solvent. The toluene/silane contaminated reagents must then be discarded as hazardous waste.
Electrospray Ionization (ESI) involves injecting and focusing a charged stream of particles held in solution into a vacuum environment. The electrospray (ES) process allows for the deposition of a film of the desired particles onto a substrate. In the ESI process, the solute molecules are directed toward the substrate based not only on their kinetic energy, but based on their movement through a pressure differential. This differential is established such that the stream of solute molecules will move toward the target chamber, which is held at a lower pressure than at the point of injection. To achieve this pressure difference, differential pumping stages are used. One example of the equipment used to accomplish this consists of two rotary vane pumps, one on each side of an orifice. The orifice size and pumping speeds are be balanced to achieve a good transmission rate of solute molecules, while preserving the pressure differential necessary to guide the solute to the target.